Total Lunar Eclipse Imaging Settings for Smart Telescopes

Confirm the timing and the Moon's height

Start with the eclipse schedule for your location. Each phase begins at a fixed universal time, but the local clock time and the Moon's altitude depend on where you are. The facts list 35° N, 50° N and 35° S as reference latitudes. At each of those latitudes the Moon sits at a different height at the same moment, so check altitude in a planetarium app set to your own coordinates rather than using a figure from another city.

Plan for the Moon to be above the horizon for the whole part of the event you want to image. A low Moon passes through more air, which dims it, reddens it and makes the image softer and more turbulent. If the Moon is low when your session starts, expect a weaker image in the early partial phases. If it sets before totality ends, you will lose the end of the event.

Totality can last up to about 1 hour 46 minutes at the longest. Most eclipses are shorter, so look up the totality length for the date you are imaging before you plan battery life and storage space.

Observers in the Southern Hemisphere at 35° S will see the Moon cross the sky along a different path than observers in the north. The image on your device may also appear rotated compared with photographs you have seen. Rotation does not change the result, because the disk is round, but it can make it harder to match your preview to a reference image. Note how the Moon's limb sits in your preview at the start, so you can recognize the phases as they progress.

Set the mode and frame the disk

Use the lunar or planetary mode if your smart telescope has one. Deep-sky modes rely on star alignment and are not designed for a bright, moving disk. They can fail or produce smeared results on the Moon. If your device offers only a general mode, choose a bright-object option and check the first few frames before you commit to a long session.

Frame the whole Moon in one shot. The expected view is the entire disk through every phase, so do not crop to a limb or a feature. Center the Moon and leave a margin on every side. The smart telescope may track the Moon, but drift can push an edge out of frame over a long session. Check the preview at the start of each block of frames and recenter if the disk is close to an edge.

If your device lets you lock the framing or set a target position, use that option. Otherwise, place the disk slightly off-center in the direction of drift, so it stays in view for longer.

Focus on a changing target

Focus on the bright limb before the eclipse starts or during the early partial phase. A sharp limb is easiest to judge while the Moon is bright. Use the device's focus aid if it has one. If not, adjust slowly while watching the preview at high zoom, and stop when the edge is sharpest.

During totality the disk is dim, and the edge is hard to see on the preview. Do not refocus in totality unless you can see the edge clearly. Changes in temperature and shifts in the telescope's position can move focus over several hours, so check it once or twice during the session. Return to the bright limb in a partial phase if one is available.

If the smart telescope has autofocus, test it on the Moon before the event. Autofocus can hunt on a dim disk and fail to settle. If focus will not lock, return to the last good manual setting and keep it for the rest of the session.

Exposure length, gain and total integration time

The exposure you need depends on the phase. The ranges below are starting points, not measurements. Use the preview histogram to adjust them.

Penumbral and partial phases

In the penumbral stage the shadow only dims the Moon slightly, and the change is subtle. Use short exposures, with gain at the low end of the device's range. Look for the bright limb near the top of the histogram without clipping to white. Clipping removes detail you cannot recover later, so leave some headroom.

As the umbra covers more of the disk, the bright area shrinks and the image dims. Lengthen the exposure gradually, watching the histogram. A typical range for the deep partial phase is a fraction of a second to about one second, depending on the device and the altitude. Many smart telescopes adjust exposure automatically. If yours does, check that it is not pushing exposures toward the upper end of its range too early.

Totality

During totality the disk turns copper and dims sharply. The exact brightness depends on the eclipse and on the air above you. Plan for exposures of about one second up to a few seconds, with gain kept moderate rather than maximal. Higher gain increases noise, and noise is harder to remove from a faint, low-contrast disk.

Watch the histogram during totality. The disk should sit well above the black point without the background dominating. If the device switches to very long exposures, check the frames for trailing and smear. The Moon moves across the sky, so very long single frames blur the edge.

Total integration time

Stacking many short frames gives a cleaner result than a few long ones. For a useful result, aim for several minutes of integrated light for each phase you intend to show, and more if you want a smoother image. A practical plan is to collect a few hundred short frames in each block of the event. Reject blurred, cloudy or out-of-focus frames before stacking.

Keep separate blocks for each phase, such as early penumbral, deep partial, totality and late partial. Separate blocks make it easier to match processing settings later, and they let you compare how the color changes through the event.

Filters

Most smart telescopes do not need a filter for this target. The Moon is bright enough during the partial phases, and the color you want to record comes from the eclipse itself. Do not use a solar filter, because the Sun is not in view and a solar filter would block the faint light you need.

A light-pollution filter can help in a suburban sky, but it changes the color balance and reduces the light reaching the sensor. Test it on the Moon before the eclipse. If the disk looks gray or dull with the filter in place, remove it.

Avoid colored filters. A color filter changes the copper tone you are trying to record and makes color balance harder to judge.

Expectations from a suburban sky

From a suburban sky with a naked-eye limit of about magnitude 5, the copper disk is easy to see without any instrument. Fine surface detail is faint during totality, and a stacked image will show more color and contrast than the eye sees. Do not expect the smart telescope to reveal much more than the disk, its color and the shadow edge.

Clouds and haze affect the result more than the telescope does. A thin layer of haze can turn the disk brownish or dim it heavily. Check the sky before the event, and keep the device warm and dry, because condensation can fog the optics during a long session.

Stacking and basic processing

Stack the frames in your device's software or on a computer. Reject frames with poor focus, clouds, trailing or strong tracking errors before stacking. Keep the accepted frames consistent within each phase, so brightness does not jump between blocks.

Basic processing is enough. Apply a stretch to bring up the faint shadow and disk edge without clipping the bright limb. Adjust color balance carefully. The copper tone is a real part of the eclipse, so avoid pushing it toward red or orange beyond what the preview shows. Reduce noise lightly, and check that you have not smoothed away the edge of the disk.

Save an unprocessed stack for each phase. That way you can reprocess the data if the first pass is too dark or too bright.

Capture plan for the night

1. Confirm the Moon's altitude and the totality time for your location.
2. Set the lunar mode, frame the whole disk and check the margin around it.
3. Focus on the bright limb and note the focus setting.
4. Shoot short exposures during the early partial phase and check the histogram.
5. Lengthen exposures gradually as the umbra grows.
6. Switch to longer exposures for totality, keeping gain moderate.
7. Check focus and framing between blocks.
8. Shoot the late partial phase, then stop before the Moon gets too low to image well.